David Atkinson asks whether nonempirical constructions can lead to genuine knowledge in science, and answers in the negative. Thought experiments, in his view, are to be commended only insofar as they eventually lead to real experiments. The claim does not rely on a general study, conceptual or historical, of thought experiments as such: the range of the paper is at once narrower and broader. Atkinson views thought experiments as commonly understood as just one kind of episode in the development of physics in which real experimentation is bypassed, and he believes that such episodes are justified only inasmuch as they are transitory stages on the way to genuine empirical inquiry. Atkinson wants to kill with one arrow what is usually regarded as two different birds: the notion that thought experiments proper can be persuasive in themselves, and the thesis that theories which cannot be brought to the tribunal of experience can nevertheless belong to science. He thus implicitly opposes three views which are commonly, albeit not universally, held: (i) some thought experiments are conclusive; (ii) some theories belong to science despite not being evidently and concretely amenable to empirical corroboration; (iii) the two issues are largely independent. The standpoint from which Atkinson operates is a rather strict form of empiricism, one which relies on a fairly sharp distinction between the conceptual and empirical dimensions of inquiry. My outlook is rather different: the conceptual and empirical seem to me to be intertwined, both conceptually, as suggested by Quine’s critique of logical positivism, and empirically, as revealed by the evidence provided by science itself in its daily and historical reality. Rather than take the high road, I propose to focus first on the critique to which Atkinson subjects Galileo’s thought experiment, and the lessons he draws from his analysis..